Looking Up: Double Cluster is double the fun

Friday

Oct 23, 2009 at 12:01 AMOct 23, 2009 at 10:18 PM

One of the most interesting star clusters in the night sky that are easy to view is the famed Double Cluster of Perseus. You can just see them with unaided eyes in a dark sky as two fuzzy patches next to each other. The view with binoculars is great, and with a backyard telescope at low power, outstanding.

Peter Becker

One of the most interesting star clusters in the night sky that are easy to view is the famed Double Cluster of Perseus. You can just see them with unaided eyes in a dark sky as two fuzzy patches next to each other. The view with binoculars is great, and with a backyard telescope at low power, outstanding.

The next clear night, before the moon gets very bright, look north for the five easily seen stars of the “W,” the constellation Cassiopeia. On an autumn evening, Cassiopeia is high in the north-northeast, with the “W” shape standing on end. The Double Cluster is a short distance below the “W.” The clusters should be quickly found scanning the area with binoculars.

With binoculars, the fuzzy patches are partly resolved into sprays of stars, compacted close together. The two clusters are so near each other, you would think they are twins.
Like everything else in the sky, these cluster are also referred by catalog numbers. One cluster is NGC 869 and the other is NGC 884. NGC stands for “New General Catalogue.” The clusters are only a few hundred light years apart, and are around 7,000 light years from the sun. A “few hundred light years” is immense on human terms but really close, galactic speaking. Imagine the brilliant, starry sky you would have from a planet near these two.

Stars in these clusters are bluish, and considered young. There are a few ruby red or orange stars here and there in the view through a telescope. Look for the red one right between the clusters.

The Double Cluster is among the myriad stars of the Milky Way Band, which passes through the constellations Perseus and Cassiopeia. A sweep of this region with binoculars, or a small telescope, is rewarding indeed, with innumerable faint stars and star clusters. One of the joys to behold is how the stars often happen to fall in lines, curves and outlines of imagined shapes. You can easily find your own “constellations,” which are known as asterisms.

Traveling the night sky with a backyard telescope, I have stumbled upon arrangements of stars that look vaguely like letters of the alphabet, circles, squares and animal shapes. You name it, you will likely find it with a lot of imagination! Very close to the Double Cluster - on the west side - I find what resembles an outline of a fish, with two curving antennae.

The way stars appear to be arranged of course is due to our perspective. Stars are at varying distances, so from other vantage points in the galaxy, our beloved constellations and lesser asterisms would disappear.

There are literally thousands of star clusters around the entire sky within reach of a small telescope, with many visible with binoculars, and a handful easily seen with unaided eyes. Each is a wonder on its own; stop and realize that these are vast star associations, bound to each other by mutual gravitation. Hopefully the ties that bind are partly out of love, as these stars have a common origin. If they were living things, we’d call them siblings. They travel space together, only very gradually spreading apart but not so much that anyone would notice in a human lifetime.

Look for the brilliant Pleiades Star Cluster, low in the northeast in the evening sky this fall. It is easier to see, higher up later at night and is one of the beacons of the coming winter evening sky.

First-quarter moon arrives Oct. 25. Monday night, the 26th, the moon is close to the bright planet Jupiter. Speaking of star clusters, a good time (clouds permitting) to see the Beehive Star Cluster will be in the early morning hours of Sunday, Nov. 1. Look low in the east about 1 a.m. or so. The red planet Mars will be shining smack dab in the center of the star cluster. Binoculars will give a great view.

Send comments and questions to pbecker@wayneindependent.com.

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